The present invention relates to a storage system for storing a data issued from a host system, more particularly to a storage controlling apparatus in the storage system connected to the host system via a fiber channel.
Preferably, computer systems should be prevented from every unexpected error to occur therein. In case such an unexpected error occurs in a computer system, it is more important to recover the system as quickly as possible than locating the error and finding the error cause so as to take countermeasures for the detected error. In particular, in case an error occurs in a storage system, the storage system must be recovered from the error before such a host system as a computer detects the error. Once the host system detects the error before the error recovery, the whole system might possibly be down (system down).
Such a controlling apparatus for a storage system is often configured as dual system consisting of a current controller and a standby controller so as to recover from errors quickly. When one controller is driven as a current controller and the other is driven as a standby controller such way, control is passed to the standby controller in case an error occurs in the current one. A quick error recovery is thus expected. Conventionally, data security has been improved by the technique. In this case, passing control to the standby controller causes the port information (WWN, port ID, etc.) of the error-detected controller to be passed to the standby controller, thereby the controller switching is done while the host system does not recognize the switching.
According to the conventional technique, even when the host system (computer) detects such a storage system error, the error-detected controller is switched to the standby one with use of a path switching program provided for the host system.